Even when the supply of inorganic nutrients to the surface is high, due to for example upwelling, the absolute concentration of nutrients in the surface may still be low.
The above statement is false. Compared to deep ocean water, water in the surface has the lesser supply of rich inorganic nutrients. But due to upwelling, the absolute concentration of nutrients in the surface will be higher.
Upwelling brings those lost/sunk nutrients, plankton and carcasses to the surface. The surface then becomes feeding grounds for fish and other ocean life.
